Workers in a section of the mammoth building had been taking apart and cleaning the filters of a large industrial filter system when the blaze occurred, he said. Dust in the filters ignited after the workers used a cutting torch to cut off some bolts.

While a fire damage wasn’t known late Tuesday afternoon, Walmsley said filter units like the one involved in the blaze can cost upwards of $100,000. The building itself was fine, but needed to be ventilated, he said.

“I would believe [the fire] was just contained to that unit, so we weren’t really worried about extension to any other areas of that building.”